Problem: Simplify the following expression: $2\sqrt{28}$.
Solution: First, try to factor a perfect square out of the radical. $= 2\sqrt{28}$ $= 2\sqrt{4 \cdot 7}$ Separate the radical and simplify. $= 2\sqrt{4} \cdot \sqrt{7}$ $= 2 \cdot 2 \cdot \sqrt{7}$ $= 4\sqrt{7}$